Improvement in steam-engine valves



tant @aient l @fil CHARLES DAWSON, OF LANE SBOROUGI-I, PENNSYLVANIA.

Letters Patent No. 89,471, dated April 27, 1869.

IMPROVEMENT IN STEAM-ENGINE VALVES.

The Schedule referred to in these Letters Patent and making part of the lama.

To all whom it may' conce/m:

Be it known that I, CHARLES DAWSON, of Lanesborough, in the county of Susquehanna, and State of' Pennsylvania, have invented a new and useful Improvement in Steam-Valves, of which the following is a full, clear, and exact description, reference being had to the accompanying drawing,`forming part of this specication, and in which- Figures 1 and 2 represent sectional elevations rat right angles to each other of my improved steam-valve as arranged in connection with the ports or passages of an engine-cylinder.

Similar letters of reference indicate corresponding parts.

This, my improvement, which I designate a compensation balance-valve, and which is applicable to locomotive and other engines, relates to valves of a partially ci'rcular character, having a rocking-movement; and

The invention consists in a novel construction of such valve, whereby, while the steam is first admitted to it from below, the same is allowed, through the agency of independent valves carried by such main valve, to act in a secondary manner upon the top of the valve, and whereby numerous advantages are obtained.

Referring to the accompanying drawing- A is' the valve, which is of a partially circular character, so as to lie on one side only of the shaft B, which rocks it, through drivers a a, arranged to gear with projections b on the inside of the valve, that is grooved orcut away on its outside face to form steameavities, c c, an intermediate exhaust-cavity, al, and lips or bearing-surfaces e e and f f.

C is a partial cylinder, forming an upper bonnet to the valve that rocks or works in close contact therein, and serving to establish, in connection with an outer cylinder or chamber, D, branches g g, for the steam from the boiler, which enters at h.

This construction dispenses with a steam-chest to the valve and causes the steam to be branched direct from the boiler to the under side of the valve, entering alternately the cavities c c, as they are brought by the rocking-movement of the valve, in communication with the lower open ends to said branches g g, the lips e e being arranged to control both the branches g g and the ports orpassages 'l i to the opposite ends of the engine-cylinder, and, so far as establishing communication of the latter passages with the exhaust, controlling the exhaust-passage or outlet k.

Either steam-cavity c c portion of the valve is provided with a puppet-valve, 'm m, arranged to open inward, so as to admit steam to the 'top or lback of the valve, in a secondary manner, as itwere, that is, after its admission, to act upon the valve from below.

The general action of the valve is similar to that ofother valves, so far as opening either port i1'. alternately to pass and exhaust steam to and from the engine-cylinder, but by the special construction hereshown, not only is a steam-chest dispensed with, but

the valve balanced in a measure and restrained from.

cutting its own face by reason of the steam being admitted to act with full boiler-pressure under the valve 4with a condensed steam or water-pressure above by the occasional passage of steam through the puppetvalves m m, which close to prevent egress of water, or condensed steam.

Said valve having a diminished boiler-pressure above it, moves with very little friction.

As compared with an ordinary slide-valve, there will be found great saving of power, also of' wear, on all the connections, rocker-shafts, links and link-blocks, eccentrics and eccentric-straps, making the engine far more easy to work or control.

What is here claimed, and desired to be secured by- OHAS. DAWSON. Witnesses:

N. R. COMFORT, A. G. BRUSH. 

